import type { Organization } from 'fhir/r4';

/**
 * The practice's own NPI, read off the Organization.
 *
 * THE SYSTEM URL IS THE STANDARD FHIR ONE and it must stay in step with the server's `NPI_SYSTEM`
 * (`aws/sam/services/api/src/utils/npi.ts`). Both halves match on it, and a client reading a different
 * spelling would show an empty field for a practice that has recorded one - which reads as "not set"
 * and invites somebody to type it again into a server that will refuse it as already claimed.
 *
 * `identifier` CARRIES MORE THAN THIS. The array also holds the account-home-patient link and is where
 * an SSN would live, so this finds its entry by system rather than taking the first one.
 */
export const NPI_SYSTEM = 'http://hl7.org/fhir/sid/us-npi';

export const readOrganizationNpi = (organization?: Organization | null): string | undefined => {
    const value = organization?.identifier
        ?.find((identifier) => identifier.system === NPI_SYSTEM)
        ?.value
        ?.trim();

    return value || undefined;
};